Paintable surface heating system using graphene nano-platelets apparatus and method

ABSTRACT

A heating device including a substrate, at least one heating layer on the substrate, and a power supply electrically connected to the at least one heating layer. The heating layer includes graphene nanomaterials. To form a layer of heating material, a liquid including graphene nanomaterials is applied to the substrate. The liquid is dried to form the at least one heating layer on the substrate. A first electrode and a second electrode are attached to the substrate. A power supply is electrically connected to the at least one heating layer on the substrate via the first electrode and the second electrode. The heating layer produces heat in the presence of power applied to the electrodes.

TECHNICAL FIELD

Various embodiments described herein relate to an apparatus for apaintable surface heating system using graphene nano-platelets. Othervarious embodiments relate to methods for making and using the paintablesurface heating system.

SUMMARY OF THE INVENTION

A device includes a heating surface element made of a paint thatincludes a nanomaterial substance. One such substance is GrapheneNano-platelets (“GNP”). GNP has a very high electrical conductivity anda very high thermal conductivity when compared to many other substances.The use of GNP provides highly uniform surface temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is pointed out with particularity in the appended claims.However, a more complete understanding of the present invention may bederived by referring to the detailed description when considered inconnection with the figures, wherein like reference numbers refer tosimilar items throughout the figures and:

FIG. 1 is a schematic view of a heating apparatus, according to anexample embodiment.

FIG. 2 is a schematic view of another heating apparatus, according toanother example embodiment.

FIG. 3 is a flow chart of a set of processes for making a GNP heater ona substrate, according to an example embodiment.

FIG. 4 is a top view of a GNP heater over glass substrate with copperelectrodes, according to an example embodiment.

FIG. 5 is a top view of a GNP heater on glass without copper electrodes,according to an example embodiment.

FIG. 6 is a top view of GNP heater of two channels on Pyrex substrate,according to an example embodiment.

FIG. 7 is a top view of a GNP heater on a wood substrate with copperelectrodes, according to an example embodiment.

FIG. 8 is a top view of a GNP heater on a cement block with copperelectrodes, according to an example embodiment.

FIG. 9 is a top view of a Ceramic tile with painted GNP heater,according to an example embodiment.

FIG. 10 is a graph of a temperature profile of the GNP heater on a woodsubstrate of FIG. 7, according to an example embodiment.

The description set out herein illustrates the various embodiments ofthe invention and such description is not intended to be construed aslimiting in any manner.

DETAILED DESCRIPTION

FIG. 1 is a schematic view of a heating apparatus 100, according to anexample embodiment. The heating apparatus 100 includes a substrate 110,and a layer of electrically conductive paint or ink 120. The beatingapparatus 100 can also include a first electrode 130 and a secondelectrode 132. The first electrode 130 and the second electrode 132 aregenerally positioned remote from one another with a portion ofelectrically conductive paint or ink 120 located between them. A sourceof power 140 is attached to the first electrode 130 and the secondelectrode 132. The power source 140 drives electrical energy through thelayer of electrically conductive paint or ink 120. Heat is produced atthe layer 120. The heating apparatus 100 is sometimes referred to as aconductive surface heater. The power source 140 can be either an AC orDC power supply. The DC power supplies would work for low-temperatureapplications, and the AC power supplies are suitable for high-powerheating source and or for high-temperature applications.

FIG. 2 is a schematic view of another heating apparatus 200, accordingto another example embodiment. The heating apparatus 200 includes manyof the same elements of the heating apparatus 200. The common elementscarry the same reference numbers. For the sake of brevity, some of thedifferences will be discussed. In the heading apparatus 200, the maindifference is that the heating apparatus is devoid of electrodes. Thepower source can be connected to selected portions of the surface 120.Generally, the power source is connected at two spots that are remotehorn one another. Electricity flows in the electrically conductive paintor ink 120 to produce heat. The power source can be connected at otherspots on the electrically conductive paint or ink 120 to produce heat.In another example embodiment, there are no separate electrodes. Theheating apparatus 200 is sometimes referred to as a conductive surfaceheater.

The electrically conductive paint or ink of nanosubstance 120 includesan electrically conductive and thermally conductive nanomaterial such,as Graphene Nano-platelets (GNP). The electric power source 140 isconnected to two ends of a surface area to provide an electric currentand power to the heater 100, 200. The conductive surface heater can takeany shape or thickness. A heater that is graphene-based provides a largeuniform surface temperature due to the intrinsic high lateral thermalconductivity of GNP. The electrically conductive surface heaters canreplace wire-based heating coils and therefore would have numerousapplications. For example, the device can be used as a heating elementin home appliances such as in replacing the heating elements offurnaces, space heater, clothes dryers, and even in the heating elementsof coffee makers and water heaters. It can also be used for heatingelectronics and other applications where external heat is needed. Incold climates locations, the surface heaters can be used in outdoorapplications such as in defrosting driveways, highways exit/enter ramps,streets sideways, and runways of airports. Other applications besidestheses are contemplated.

FIG. 3 is a flowchart of a method 300 for making a GNP heater on asubstrate, according to an example embodiment. The method 300 can alsobe thought of as a set of processes for making the GNP heater on asubstrate. The method 300 includes providing a solvent 310, and addinggraphene nano-platelets to solvent 312. The graphene nano-platelets andsolvent are mixed using sonication 313. Sonication is the act ofapplying sound energy to agitate particles in a sample. Ultrasonicfrequencies are used in some embodiments. The method 300 also includesadding a binder 314 and sonicates the mixture. The mixture of thesolvent, the graphene nano-platelets, and the binder is applied to asurface or a substrate 316. The mixture is applied by spraying,painting, printing or the like, the mixture of the solvent, the graphenenano-platelets and the binder onto a surface or substrate. Metalelectrodes, in some embodiments, are added 318, and a power supply iselectrically connected to the electrodes 320. In some embodiments, athermocouple is added 322 to control temperature. The method 300 furtherincludes using the connected power supply to control temperature 324.

In making the paint, that includes a solvent and graphenenano-platelets, the unique size and platelet morphology of GNP makethese particles especially effective at providing barrier properties,while their pure graphitic composition makes them excellent electricaland thermal conductors. Unlike many other additives, GNP can improve themechanical properties of the paintable heater, such as stiffness,strength and surface hardness.

Moreover, the ease by which a paint can be applied to diverse substancesand surfaces can be used in making efficient heating devices providedthat an electric source and electrodes are present. Paintable heatingdevices can lead to the development of many applications such as atwo-dimensional heating device made of paints or coating of GNP indifferent binders, matrix materials and surfactants. The differentbinders, matrix materials and surfactants or solvents can be varied todesign the paint or ink for specific applications depending on thedesired final temperature and or for the environment in which the ink orpaint will operate in. The conductive surface area is connected toelectrodes at their terminals which are hence also connected to anelectric power supply. The current flowing across the conductive paintheats the object while the predetermined final temperature is controlledby the use of a surface thermocouple, which controls the magnitude ofcurrent to the device and hence the amount of heat produced which inturn affects the temperature of the device.

FIG. 4 is a top view of a GNP heater 400 formed over a glass substrate410 with copper electrodes 430, 432, according to an example embodiment.The paint or ink is formed with GNP therein. The paint or ink is asolvent or surfactant that has GNP mixed therein. The paint or ink isalso provided with a binder. The paint or ink is formed so that it canbe sprayed or printed onto the substrate 410 to form a thin film orlayer of heater material 420. The paint or ink is sprayed, printed, orotherwise applied to the material. Electrodes 430 and 432 are added tothe ends of the sprayed or printed material. A power supply (shown inFIGS. 1 and 2) is then applied to the electrodes 430, 432. Athermocouple can be used to control the magnitude of the current appliedto the electrodes 430, 432 and the heater material 420 as applied to thesubstrate 410.

FIG. 5 is a top view of a GNP heater 500 formed on glass without copperelectrodes, according to an example embodiment. The paint or ink isformed with GNP therein. The paint or ink is a solvent or surfactantthat has GNP mixed therein. The paint or ink is also provided with abinder. The paint or ink is formed so that it can be sprayed or printedonto the substrate 510 to form a thin film or layer of heater material520. The paint or ink is sprayed, printed, or otherwise applied to thematerial. A power supply (shown in FIGS. 1 and 2) is then applied to theheater material 520 at two locations remote from one another. Athermocouple can be used to control the magnitude of the current appliedto the heater material 520 as applied to the substrate 510.

FIG. 6 is a top view of GNP heater 600 of two channels on Pyrexsubstrate 610, according to an example embodiment. The paint or ink isformed with GNP therein. The paint or ink is a solvent or surfactantthat has GNP mixed therein. The paint or ink is also provided with abinder. The paint or ink is formed so that it can be sprayed or printedor otherwise applied onto the Pyrex substrate 610 to form a thin film orlayer of heater material 620. In this embodiment, the heater material620 is formed as a first channel 621 and a second channel 622. Thechannel 621 and the channel 622 are isolated from one another along aportion of their respective paths. The paint or ink is sprayed, printed,or otherwise applied to the material. Electrodes 630 and 632 are addedto the ends of the sprayed or printed material 620. A power supply(shown in FIGS. 1 and 2) is then applied to the electrodes 630, 632. Athermocouple can be used to control the magnitude of the current appliedto the electrodes 630, 632 and the heater material 620 as applied to thesubstrate 610.

FIG. 7 is a top view of a GNP heater 700 on the wood substrate 710 withcopper electrodes 730, 732, according to an example embodiment. Thepaint or ink is formed with GNP therein. The paint or ink is a solventor surfactant that has GNP mixed therein. The paint or ink is alsoprovided with a binder. The paint or ink is formed so that it can besprayed or printed onto the wood substrate 710 to form a thin film orlayer of heater material 720. The paint or ink is sprayed, printed, orotherwise applied to the material. Electrodes 730 and 732 are added tothe ends of the sprayed or printed material. A power supply (shown inFIGS. 1 and 2) is then applied to the electrodes 730, 732. Athermocouple can be used to control the magnitude of the current appliedto the electrodes 730, 732 and the heater material 720 as applied to thesubstrate 710.

FIG. 8 is a top view of a GNP heater 800 on cement block substrate 810with copper electrodes 830, 832, according to an example embodiment. Thepaint or ink is formed with GNP therein. The paint or ink is a solventor surfactant that has GNP mixed therein. The paint or ink is alsoprovided with a binder. The paint or ink is formed so that it can besprayed or printed onto the substrate 810 to form a thin film or layerof heater material 820. The paint or ink is sprayed, printed, orotherwise applied to the material. Electrodes 830 and 832 are added tothe ends of the sprayed or printed material. A power supply (shown inFIGS. 1 and 2) is then applied to the electrodes 830, 832. Athermocouple can be used to control the magnitude of the current appliedto the electrodes 830, 832 and the heater material 820 as applied to thesubstrate 810.

FIG. 9 is a top view of a Ceramic tile with painted GNP heater 900,according to an example embodiment. The GNP heater 900 is formed on asubstrate 910 with copper electrodes 930, 932, according to an exampleembodiment. The paint or ink is formed with GNP therein. The paint orink is a solvent or surfactant that has GNP mixed therein. The paint orink is also provided with a binder. The paint or ink is formed so thatit can be sprayed or printed onto the substrate 910 to form a thin filmor layer of heater material 920. The paint or ink is sprayed, printed,or otherwise applied to the material. In this embodiment, the heatermaterial is formed as a plurality of separated channel 921, 922, 923,924. Electrodes 930 and 932 are added to the ends of the sprayed orprinted material. A power supply (shown in FIGS. 1 and 2) is thenapplied to the electrodes 830, 932. A thermocouple can be used tocontrol the magnitude of the current applied to the electrodes 930, 932and the heater material 920 as applied to the substrate 910.

Still other embodiments include a heater that has a plurality of paintedor printed heater layers on a substrate.

Further embodiments include:

The heating device discussed above having graphene nano-platelets Oxideor edge-functionalized graphene nano-platelets. In addition, the heatingdevice could be formed with of exfoliated graphite exfoliated graphiteoxides. In other example embodiments, the heating device can be madeusing any/and all two-dimensional nanomaterials of high electricalconductivity.

The substrate used can include polymers of high glass transition, glass,metals, Pyrex, cement, concrete, wood, ceramics, a variety of tilematerials, an electrically conductive material, an electrically isolatedmaterial, a mechanically strong material, a flexible material, a porousmaterial, a nonporous material.

It is further contemplated that the paint could be oil based or acrylicpaint. In one embodiment, graphene nano-platelets in an oil-based oracrylic paint could contain 0.1% to 1% graphene nano-platelets byweight. The amount of graphene nano-platelets can be higher than 1% orlower than 0.1% of nanomaterials depending on the expected finaloperating temperature of the heater. The graphene nano-platelets couldbe used with a pigment, a binder, a resin, an extender, a solvent or athinner of either an organic solvent or water and additives. In oneembodiment, graphene nano-platelets are initially dissolved in thinnerbefore adding it to an over the shell paint. The paint can be applied asa spray on substrates, printed on the substrates, applied in a 3-dprinting operation, or as rollover printings.

The liquid heating device using graphene nano-platelets can beincorporated with cement to defrost driveways of houses and highways,runways of airports, highway bridge decks in cold climates. The heaterscould also be used as the heating source of home furnaces. The heaterscould also be used as the heating source of home tiles. Alsocontemplated is a heating device as described above to be used foroutdoor applications by attaching it to an energy source of a solarpanel.

Various implementations and testing procedures for the GNP surfaceheater are illustrated in the following examples.

EXAMPLE 1

Materials: GNP (xGnp-M-5) was purchased from XG Sciences and was usedwithout further modifications GNP was dispersed in Isopropanol Alcoholusing probe sonication. A glass plate was used as an example of atesting surface. The Glass surface was chemically etched withconcentrated sulfuric acid for 5 minutes followed by multiple washeswith deionized (DI) water to remove all traces of the acid.

A rectangular heater of a GNP strip was painted on the glass using abrush. At the ends of the strip were placed a copper foil tape aselectrodes. The rectangular paint overlapped with the copper electrodesto form an ohmic contact with the surface heater. The copper created lowresistance contacts for the electric inputs.

The GNP heater was electrified to test their heating properties. Adirect current power supply (25V, 0.9 Am) was used to supply the inputpower. The current in the circuit was measured using a CEN-Teck powermeter. The initial sheet resistance between the two electrodes was 13Ohm at room temperature (22 C). Upon applying an external 25 volts tothe electrodes, a temperature rise to around 68 C after 60 seconds ofactive current was observed. The temperatures of different spots on theheater surface were measured using a non-contact laser thermometer. Alsoobserved was a rapid drop (tens of seconds) in temperature when theelectric source was disconnected. The rapid drop in the temperature ofthe GNP heater is due to the high lateral thermal conductivity ofgraphene.

EXAMPLE 2

Another heater sample was tested using different graphene preparation.

Materials: Graphene sample was chemically processed to increaseexfoliation of the nano-platelets under basic pH condition. A 3%hydrogen peroxide was added slowly to the graphene solution while mixingand was kept at room temperature for 24 hours. The sample was filteredand washed multiple times with deionized (“DI”) water to remove saltsand ions until the pH of the solution dropped to around pH 7. An inksolution of the exfoliated sample was made with the addition of a GumArabic binder without further modification to paint a new glass plate ofcircular surface shape.

Two electrodes were placed at opposite end of the circle while measuringthe surface resistance between the two electrodes. A current was alsoapplied to the painted film and the temperature rise was measured atdifferent locations on the glass heater. The GNP paint film was stableeven in the absence of binders even after heating events. Again wenoticed a rapid rise in temperature of the glass surface.

The GNP film was painted on a variety of surface substrates of differentmaterials such on Pyrex (FIG. 6), plastic, paper, wood block (FIG. 7),and cement slab (FIG. 8). In all examples, the same rapid rise insample's temperature followed by lateral spreading of heat on thesurface was observed. The rate at which temperature increases depends onthe electrical resistance of the film (between electrodes). The lateraltemperature equilibrium on the surface is related to the concentrationof GNP, their microscopic orientation across (effective thermalconductivity), and the material composition of the substrate.

EXAMPLE 3

The performance of GNP painted heater on cement substrate of 0.3 cmthickness of the middle section and 0.6 cm at one side of its boundary(FIG. 8) was tested. Using a rectangular shape GNP coat on cement arapid rise in temperature of the substrate (280 C) with the appliedelectric source was observed. In this example, the initial electricalresistance of the device as measured at both ends of the coat was around40 ohm. The temperature rise of the surface area of the cement was morenoticeable at the edge of the cement slab. It is also important tonotice that the cement sample that used contained less than 1% of GNP inits composition, which contributed to the enhancement of the thermalconductivity of the cement surface. However, the electrical conductivityof the cement was very small and much less than the detection limit ofthe instrument. The instrument indicated that current remained withinthe GNP heater.

The heating profile of GNP painted heater on wood (FIG. 7) isillustrated in FIG. 10. As expected, the temperature increase is not asmuch as that of other substrates. FIG. 10 is a graph of a temperatureprofile of the GNP heater on a wood substrate of FIG. 7, according to anexample embodiment. In the graph, the temperature is on the vertical ory-axis 1010 and the time in minutes is on the horizontal or x-axis 1020.As shown, the temperature rises during an initial time and then dropsrapidly after several minutes when the current is removed from theheater 700.

A comparison with other types of materials:

In order to test the performance of Graphene heater in compati son toother carbon materials, a heater paint made of conductive wire glueavailable from Radio Shack was tested. The RadioShack Graphite-FilledConductive Wire Glue contains black carbon pigment. The electricalresistance of a rectangle strip of the black ink of 3 by 3 cm indicatesan electrical resistance of around 1.04 M Ohms. When this heating devicewas connected to an electrical source, no heating at all was observed.The lack of heating in this system reflects the high resistivity of theblack carbon and its matrix in comparison to GNP systems.

In summary, the platform technology of this application is for apaintable heater. This means that a material can be spread on anysurface in the form of a paint, ink or suspension, to form a film whichupon drying becomes an electrically resistive film. When current is runthrough the film, it becomes a heater.

A sample preparation includes suspending 2 grams of graphenenano-platelets, such as M-5 from XG Sciences, 3101 Grand Oak Drive,Lansing, Mich. 48911, in 250 ml of water. The suspension is sonicatedfor a total of 20 minutes with 1 minute on followed by 20 seconds offcycle. Then 5 ml of 93% Sulfuric acid was slowly added to the suspensionand mixed well. After mixing, we slowly added 10 ml of 3% hydrogenperoxide to further exfoliate the graphene nano-platelets. The solutionwas continuously mixed for 10 minutes and then stored in a cold place.The mix was left alone for a few days. After the few days, the mix isthen diluted with 1 to 5 in volume with deionized (di) water. Thesolution was allowed to settle and the acid was washed three times by diwater. After removing excess water, the suspended nano-platelets areagain resuspended in 200 ml of fresh water. The final suspension wasmade acidic by adding a 10 ml of Acetic acid and used as is.

In another sample preparation, the M-5 graphene nano-platelet wassuspended at a concentration of 2 g/250 ml of 91% Isopropyl Alcoholusing a probe sonicator, 200 W, and used as received.

In yet another different sample preparation, a mortar and pestle areused to grind 0.5 grams of M-5 graphene nano-platelets. Once thegraphene is a fine even powder, we slowly added a 10 ml of di water tothe dry powder and continue the grinding process to remove any lumpsuntil we obtained a fine paste. In a separate container, egg tempera wasprepared using only the yolk of a fresh egg that is diluted with equalamount of di water. A few drops of Acetic acid is added to the yolk mixfor preservation. A small amount of the graphene paste is slowly mixedwith equal amount of the yolk paste to form the final paint. Theconcentrated tempera/graphene mix is then applied to the substrate toform the heating surface. Two copper electrodes were used on theopposite sides of the film and the dry resistance between them ismeasured. If the resistance is high, more applications are added untilwe reached the desired resistance.

Still another sample preparation method for graphene nano-platelet paintor graphene nano-platelet ink includes the dispersion of xGnP R-7 fromXG Sciences, 3101 Grand Oak Drive, Lansing, Mich. 48911, USA in waterglass matrix. A 20 grams of Water glass sample from Rutland Fire ClayCo., 38 Merchants Row, Rutland, Vt., 05701 USA, was used as received. Itwas first diluted with 20 grams of water before adding 2 grams of xGnPR-7 to the mix. The mix was vigorously shaken in a tightly covered 100ml container for a few minutes before its use. In another preparation,the graphene in water glass system was dispersed using a probe sonicatorto obtain a better dispersal. After mixing, the graphene sample waspainted on ceramic tile that contained copper electrodes at the twoopposite edges using a hand brush. The sample was left to dry at roomtemperature for 24 hours. The electric resistance of the dry filmbetween the two electrodes was measured with an electric meter. Theapplication of new wet film, drying, and the measurements of theelectric resistance were repeated over a few days in order to lower thefinal resistance. The resistance of the film decreased with theincreasing number of film applications. Once the desired resistance orheating power is reached, no new film was added. The value of theheating power of the film is related to its final resistance and theapplied external voltage, P=V²/R, where R is the final resistance and Vis the applied voltage.

Assuming the formation of a uniform resistive surface, there is arelationship between the total resistance and the power generation as inthe following P=V˜2/R, where V is the applied voltage and the R is theelectrical resistance. It is clear that generating a high-power heatingsource requires film with low resistance or the use of a high externalvoltage source. The power density for square length can be calculated bynormalizing the total two-dimensional lengths to the specific area ofinterest.

The above can be used as paints or inks.

It should be understood that enhancements to the physical and chemicalproperties of GNP and derivatives for this application are contemplated.It should be noted that other electrically conductive inks and paintscould be utilized or modified for the heating applications like thosedescribed above. In addition, it is contemplated that these inks andcoatings can be used and may work in diverse synthetic polymers.However, the different glass and melting temperatures of the differentpolymers have to be considered when contemplating heaters that can bindto these substrates while provides heating without damaging or alteringthe physical or chemical properties of these materials. In someembodiments, the graphene paint could be placed or sandwiched betweentwo polymers matrices and be used as a conductive heating element. Instill further example embodiments, the polymer layers and the graphenepaint can be layered so that multiple layers of graphene paint or filmcan be sandwiched between adjacent layers of polymer. When sandwichedbetween tow polymer matrices, the graphene paint can be used as aconductive heating element, such as those described at other locationsin this application.

A large number of specific applications for the above-described heatersis contemplated. Some of the specific applications are listed below. Itshould be noted that this list is not inclusive but is a sampling of alarge number of possible applications of the heater invention.

-   -   Outdoor:    -   The heating device can be implemented in flexible long strips,        which can be enclosed into or under modern concrete or cement        composition of smart driveways. These heating elements can        provide external heat during winter seasons which can be        implemented in the following:        -   Defrosting driveways by applying painting strips of electric            heating elements under driveways for defrosting.        -   Defrosting busy streets and sideways to prevent the            formation of Ice on the roads.        -   Defrosting runways in airports by applying of painting strip            of electric heaters under runways and therefore reduces            plans slipping or gliding on runways.        -   Heating blanket for outdoor applications or construction in            which the temperature of outdoor objects needs to stay above            a specific temperature.        -   The increased production of renewable solar energy can            directly be used as a local and alternative energy source            for outdoor surface heating. One can think of many other            applications for the use of GNP surface heaters in addition            to ones mentioned here.        -   Outer space: The two-dimensional surface heater can be used            in special applications such as in space environments by            designing an on-demand heater for the specific target by            simply apply the coating to any element followed by            activating the heating surface with an electric source.            Giving the extreme cost of bringing heavyweights electric            coils and metals to space orbits, one can easily replace            many of these with a much lighter container of GNP            conductive paint that can be transformed into any types of            heaters as long there is an electric power source. Heating            construction and deconstruction are easy to implement in            these circumstances since the same heater can be erased            using chemicals such as alcohol once the heating device is            not needed.    -   Indoor:        -   Heating blankets for home and hospital usages.        -   The electric heating surface can be used in any application            that requires the use of strong heating sources such as            water heaters and coffee makers. Having the heating source            in close contact with the object of heating reduces the            thermal resistance and therefore provides an efficient            heating source.        -   Floor heating: The graphene heating coats can be            incorporated into ceramic tiles by sandwiching them as a            conductive film within the content of tiles. By connecting            numbers of graphene modified tiles to an electric source,            one can create a heated floor with little modification of            existing construction by using an electric source,            thermocouples and thermostat to control the final            temperature. This technique can reduce the building cost and            minimizes the complexity of the design since there are no            needs for an external ventilation system as in the case of            gas heating systems. Moreover, they can be easily added, for            example, to any existing bathroom by just changing the tiles            to heat their floor without too many modifications of a            given home design. Using GNP modified tiles is much            affordable and easier to implement than using Carbon            nanotubes which require spatial alignment beside their high            cost        -   Home electric furnaces: Current gas furnaces can be modified            or replaced with more efficient and less polluting electric            heating sources using our conductive surface heating            element. Current electric furnaces use electric heating            coils as the source of heat, instead of burning gas or oil.            However, coils are small and therefore not highly efficient            despite their large consumption of electric energy. The            increased surface area of the painted heaters can enhance            the overall thermal delivery of heat to the air in furnaces.            Moreover, the surface heater can be painted directly on the            heat exchanger of existing gas furnaces and therefore            enhance their efficiency by reducing their thermal            resistance.

A heating device including a substrate, at least one heating layer onthe substrate, and a power supply electrically connected to the at leastone heating layer. The heating layer includes graphene nanomaterials. Toform a layer of heating material, a liquid including graphenenanomaterials is applied to the substrate. The liquid is dried to formthe at least one heating layer on the substrate. A first electrode and asecond electrode are attached to the substrate. A power supply iselectrically connected to the at least one heating layer on thesubstrate via the first electrode and the second electrode. The heatinglayer produces heat in the presence of power applied to the electrodes.The graphene nanomaterials, such as graphene nanoparticles, in theheating layer dissipate the electricity in the heating layer in responseto the application of power to the heating layer. In some embodiments, aplurality of heating layers are applied to the substrate to form theheating device. In still further embodiments, the resistance between thefirst electrode and the second electrode is measured after theapplication of the heating layer. In some embodiments, additionalheating layers are applied until a desired resistance between the firstelectrode and the second electrode is achieved. The heating device, insome example embodiments, includes a first electrode coupled to the atleast one heating layer on the substrate, and a second electrode coupledto the at least one heating layer on the substrate at a location remotefrom the first electrode.

In some embodiments, the power source for the heating device is a DC(direct current) power source. In other embodiments, the power sourcefor the heating device is an AC (alternating current) power source.

The liquid including the graphene nanomaterials or graphenenanoparticles can be a paint or an ink. The ink is capable of beingprinted onto the substrate. The graphene nanomaterials can includegraphene nano-platelets, in one embodiment. In another embodiment, thegraphene nanomaterials can include graphene oxide nano-platelets. Instill other example embodiments, the graphene nanomaterials includeedge-functionalized graphene nano-platelets.

In one example embodiment, the substrate of the heating devices made ofglass, a dielectric material, an electrically isolated material, apolymer material, or the like.

The heating device, in still another embodiment, includes a cover layercovering the heating layer. The heating layer is sandwiched between theelectrically insulating substrate and the cover layer. In anotherexample embodiment, a heating layer is sandwiched between moistureinsulating substrate and the cover layer.

A method of forming a heating device includes suspending an amount ofgraphene nano-platelets in a liquid, sonicating the liquid, andspreading the liquid and graphene nano-platelet mixture on a substrateas a film. The substrate includes a first electrode and a secondelectrode spaced away from the first. The liquid and graphenenano-platelet mixture is dried. The resistance between the firstelectrode and the second electrode is measured. In some embodiments, thespreading and drying spreading of the liquid and graphene nano-plateletmixture on a substrate are repeated. The resistance between theelectrodes is measured. The spread and drying can be continued until apredetermined final resistance between the first electrode and thesecond electrode is reached. In one embodiment, the amount of suspendednano-platelets is in a range of 0.1% to 1% graphene nano-platelets byweight. In another example embodiment, amount of suspended platelets isvaried to vary the final resistance, and the amount of heating of theheating device. The foregoing description of the specific embodimentsreveals the general nature of the invention sufficiently that otherscan, by applying current knowledge, readily modify and/or adapt forvarious applications without departing from the concept, and thereforesuch adaptations and modifications are intended to be comprehendedwithin the meaning and range of equivalents of the disclosedembodiments.

It is to be understood that the phraseology or terminology employedherein is for the purpose of description and not of limitation.Accordingly, the invention is intended to embrace all such alternatives,modifications, equivalents and variations as fall within the spirit andbroad scope of the appended claims.

The invention claimed is:
 1. A heating device comprising; a substrate; aliquid including graphene nanomaterials applied to the substrate andallowed to dry to form at least one heating layer on the substrate; anda power supply electrically connected to the at least one heating layeron the substrate, the heating layer producing heat in the presence ofpower, the graphene nanoparticles in the heating layer dissipating theelectricity in the heating layer in response to the application of powerto the heating layer.
 2. The heating device of claim 1 wherein theheating layer is comprised of a plurality of layers.
 3. The heatingdevice of claim 1 further comprising; a first electrode coupled to theat least one heating layer on the substrate; and a second electrodecoupled to the at least one heating layer on the substrate at a locationremote from the first electrode.
 4. The heating device of claim 1wherein the power source is a DC (direct current) power source.
 5. Theheating device of claim 1 wherein the power source is an AC (alternatingcurrent) power source.
 6. The heating device of claim 1 wherein theliquid including the graphene particles is a paint.
 7. The heatingdevice of claim 1 wherein the liquid including the graphene particles isan ink capable of being printed onto the substrate.
 8. The heatingdevice of claim 1 wherein the graphene nanomaterials include graphenenano-platelets.
 9. The heating device of claim 1 wherein the graphenenanomaterials include graphene Oxide nano-platelets.
 10. The heatingdevice of claim 1 wherein the graphene nanomaterials includeedge-functionalized graphene nano-platelets.
 11. The heating device ofclaim 1 wherein the substrate is made of glass.
 12. The heating deviceof claim 1 wherein the substrate is made of a dielectric material. 13.The heating device of claim 1 wherein the substrate is made of anelectrically isolated material.
 14. The heating device of claim 1wherein the substrate is made of a polymer material.
 15. The heatingdevice of claim 1 further comprising a cover layer covering the heatinglayer.
 16. The heating device of claim 15 wherein the heating layer issandwiched between the electrically insulating substrate and the coverlayer.
 17. The heating device of claim 15 wherein the heating layer issandwiched between moisture insulating substrate and the cover layer.18. A method of forming a heating device comprising: suspending anamount of graphene nano-platelets in a liquid; sonicating the liquid;spreading the liquid and graphene nano-platelet mixture on a substrateas a film, the substrate including a first electrode and a secondelectrode spaced away from the first; and drying the liquid and graphenenano-platelet mixture; repeating the spreading and drying, untilreaching predetermined final resistance between the first electrode andthe second electrode.
 19. The method of claim 17 wherein the amount ofsuspended nano-platelets is in a range of 0.1% to 1% graphenenano-platelets by weight.
 20. The method of claim 17 wherein the amountof suspended nano-platelets is varied to vary the final resistance, andthe amount of heating of the heating device.